Calculating calorie usage/needs on longer backpacking trips

[Brad Rogers]

Is there an easy way to calculate calorie burn (and therefore needs) on a backpacking trip?  If so how does one adjust between say on trail trips @3mph and off trail trips with heavy brush, talus, moraine, etc where you may travel 1mph? What about adjusting between trips with a 20lb pack vs a 40lb pack?

I have a two week trip coming up and am trying to calculate how much weight I may lose.  I know 1lb = 3500 calories and my BMR is 1692 calories per day.

I have seen a Mayo Clinic report that a 160lb person (pretty representative of me at 6ft 162lb) burns 511 calories per hour.  If I walk for 9 hours that would be 4599 calories.  Do I add my BMR to that?  If so that is 6291 calories per day burned.

If I am carrying 2800 calories per day that means I am running at a deficit of 3491 calories per day.  Is that sustainable for two weeks?  I would lose right at 14lbs.

 

[Jerry Adams]

Try carrying that weight which should be close, then weigh yourself afterwards to see what to do for next trip.

I weigh myself immediately after, and I’m frequently a couple pounds lighter, but I gain it all back after a couple days.  I assume this is the weight of food in transit through my digestive system and water stored wherever in my body.

My last couple trips were hot (for me) and I lost 4 pounds, but gained it all back after a couple days.  I assume the extra couple pounds were water.  During the trip I drank a lot of water but got behind a couple times, my pee was fairly yellow.

At home I eat and drink way more than necessary, so I carry around a few pounds of partially digested food.  I don’t do more than a week at a time and I don’t think I ever eat so little that I start using stored body fat.  But I eat less than half as much so have less food partially digested.

 

[Nick Gatel]

You are over thinking this. You’ve been doing this long enough that you should be able to assemble food needs based on experience without a lot of calculation.

Coming up with formulas is very difficult because each of us is so different. The better one’s physical condition, the more efficient their bodies are. Given your height and weight, losing 14 lbs in 14 days is probably too much, but not dangerous to your health.

Looks like your food is calculated on 1.5 lbs per day, which is about what I bring on strenuous trips of 4 – 7 days. When I go beyond 10 days I up it to 2 lbs per day; meaning I will eat 1 PPD the first couple of days and towards the end almost 3 PPD. There is no formula for me to ramp up the food intake during the trip, just eat what I need, with any eye to try and not bring back a bunch of food or run out of food before the end of the trip. No science here, just what I have learned about myself through experience.

I also don’t spend time trying to divide up protein, fats, and carbs to obtain some sort of equilibrium. I know what foods I like on the trail. Often what we crave on the trail are the foods our bodies tell us we need.

[Lester Moore]

Jerry’s method of trial and error seems like the ideal, personalized approach to this calculating your food needs. I’ve also seen the following rule of thumb for food needs for longer trips:

• First two weeks: 1.4 lbs of food per day
• Two to four weeks: 1.75 lbs/day
• Four weeks or longer: 2+ lbs/day

You can probably perform fine with moderate weight loss over a shorter (2 or 3 week) trip, but on a longer trip, losing weight every week is obviously not sustainable.

[Matthew / BPL]

YMMV and the JMT is my only trail experience longer than 3 nights but I’ve found that I’m just not hungry enough to put away more than ~3000cal/day. I lost some weight on the JMT and gained it back quickly.

I’m curious to try Maltodextrin as a caloric bump throughout the day. I do like to drink a lot while backpacking…

[Brad Rogers]

Yes, I am sure I am over thinking this.  I never thought much about the food I took until six years ago, when I had to use a bear can for the first time.  The past couple of years I have hit the wall a few times (something I never used to do) and really struggled the last 500 feet of a 4500 climb for example wondering if I was putting the right fuel in my body.

Our bodies are amazing things, able to metabolize just about anything, but I have started (over) thinking about what foods give me an advantage over others

[Pedestrian]

For those days when you feel you need an extra boost it’s best to carry a few gels and take one before the big climb. IME caffeinated gels can be pretty effective.

On a typical 8-9 day trip I find myself reaching for the gel a couple of times and they do work wonders. Is it just placebo effect or something “real” I couldn’t tell you….

Studies have shown that just a small amount of carbs given to athletes on the verge of hitting the wall seems to help them ward off the feeling and keep exercising. It’s been theorized that as soon as the receptors on the tongue and in the mouth detect the presence of nutrition, they signal the brain to release glycogen held in reserve.
So it’s not the ingested carbs fuel the activity but the glycogen reserves that are instantly mobilized. This is all theoretical and AFAIK has not been established.

[Nick Gatel]

Maybe Tom Kirchner will see your post and chime in. He’s got some account problems and might not be able to get PM’s.

Tom is one of the more knowledgeable people here when it comes to performance and nutrition,

For me I just plod along and those high elevation gains just mean more rest stops, candy bars, jerky and potato chips.

[Jerry Adams]

I can think of one time I “hit the wall”

I’m not sure whether it was water or food.  I did quite a few miles.  It was raining so I didn’t feel like stopping to eat or drink.  I now always stop and eat several times per day, drink every hour or so.

It’s not so much how much food per day, but just remembering to eat some while hiking.

I think I’ve been confused with Nick.  That’s a scary thought : )

[Hiking Malto]

Here is Malto’s not so secret guide to caloric burn.  On typical letter trails my best estimate is that you burn your weight  in calories per mile.  So for me, I weigh in, gear and all, at about 200lb.  I will be hiking the CT in a couple of weeks targeting a 35mpd pace.  I estimate that I will burn 7000 calories per day.  Will I eat 7000 calories per day, no way.  I will target about 5000 and run a 2000 calorie deficit which will result in an estimated 8lb weight loss in that 14-16 day duration.  This is about the longest that I would run this deficit before kicking in the eating full bore.  I was eating 6000-8000 calories on my PCT in ’11 hiking about this pace.  I maintained my weight for the last 1500 miles.  I only hit the wall once on that hike as I was running low on food going into Big Bear.

I should probably mention that everyone’s ability to burn fat will be different.  I do a fair amount of very high mileage days running a deficit of 3000-4000 calories per day so my body has unwilling learned to adapt.  On trips like those I eat half my body weight per mile (300 calories per hour) almost exclusively carbs.

 

 

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